Embodiments of the invention relate to aircraft environmental control systems, and more particularly, to a gas turbine engine compressor air supply of an aircraft environmental control system.
In a typical gas turbine engine, a compressor compresses air and passes that air along a primary flow path to a combustor where it is mixed with fuel and combusted. The combusted mixture expands and is passed to a turbine, which is forced to rotate due to the passing combusted mixture. When used on an aircraft, the primary purpose of this system is to provide propulsive force for the aircraft.
In some gas turbine engines, a portion of the air compressed by the compressor is diverted from the primary flow path to a bleed inlet of a bleed air system. This compressed bleed air can be used for a variety of purposes, such as to de-ice a wing or to provide pressurized air to a cabin of the aircraft. Because the bleed air is often at an undesirably high temperature, a heat exchanger is used to cool the bleed air. Bleeding off and cooling compressed air typically does not generate thrust, thus reducing the efficiency of the compressor and the entire gas turbine engine. Moreover, the heat exchanger takes up a relatively large amount of space and can increase the overall weight of the bleed air system. The higher the pressure of the compressed bleed air the greater the efficiency debit to the gas turbine engine.